1. Field of the Invention
The present invention relates to an adjustable threshold assembly for disposition below a door assembly.
2. Description of the Related Art
Various adjustable threshold assemblies are known in the prior art and typically include a sill, a base, and a rail. The threshold assembly is disposed below a door assembly. The door assembly typically includes a hinged door and the rail is disposed on the base below the hinged door. The height of the rail may be adjusted relative to the base to create a water-tight, air-tight, and debris-tight seal between the rail and a bottom edge of the door. In other words, instead of varying the height of the door to accommodate the threshold, the height of the threshold is varied to accommodate the height of the bottom edge of the door.
Traditionally, the sill includes a rail bar disposed on the base below the rail. Holes are defined by the rail bar to align with holes defined by the base. Holes defined by the rail are in alignment with the holes in the base and the holes in the rail bar. Threaded fasteners are rotationally retained in the holes in the rail and extend through the holes in the rail bar and threadedly engage the holes in the base. The height of the rail relative to the base may be adjusted by turning the threaded fasteners. The rail bar on the sill makes the sill “handed,” or in other words a unique sill must be created for differing door assemblies. For example, in a door assembly having the hinged door to the left of a fixed panel, the rail and the rail bar must be disposed on a left side of the base below the hinged door. Alternatively, a door assembly having the hinged door to the right of the fixed panel requires that the rail and the rail bar be disposed on a right side of the base below the hinged door. The requirement to manufacture the unique sill for differing door assemblies is cumbersome.
U.S. Pat. No. 5,517,788 to McGough et al discloses a threshold assembly including a non-handed sill that does not include a rail bar. McGough discloses a base defining a channel, a rail disposed on the base and defining holes spaced along the rail, nuts pressed into the channel, and screws extending though the holes in the rail to threadedly engage the nut to attach the rail to the base. The elimination of the rail bar makes the sill non-handed so that the sill may be used in the threshold assembly regardless of whether the hinged door is to the right or to the left of the fixed panel. However, the McGough patent uses nuts that do not slide within the channel which thereby creates difficulties if the rail must be moved to a different portion of the base for disposition below the hinged door.
U.S. Patent Application Publication 2004/0200152 to Khanlarian discloses t-shaped nuts that are slideably engaged in a t-shaped channel in a base. Threaded fasteners are retained by the rail and threadedly engage the t-shaped nuts. The t-shaped nut includes a platform and a shaft extending upwardly from the platform. The t-shape nuts may be slid along the channel such that the rail may be slid to any position along the channel for disposition below a hinged door. When a person steps on the rail, a load is exerted on the nut. Traditionally, the t-shaped nut is made of a strong material such as metal to withstand force exerted on the nut to prevent fracture of the platform or the shaft, especially at the intersection of the platform and the shaft. In other words, the t-shape of the nuts and the channel limits the type of material the nut can be made of to a strong material such as metal such that the material is strong and durable to withstand the force exerted on the nut. The metal nuts may rust or corrode over time thereby creating difficulty in adjusting the height of the rail relative to the base.
It is desirable to manufacture a nut that is shaped such that the nut may be formed from a wide range of materials and yet be durable and strong enough to withstand forces exerted on the nut. More specifically, it is desirable to manufacture a strong and durable nut that is shaped such that the nut may be made from an increased range of materials such as a resin component.